David Harris is an Australian physicist and science journalist. He previously presented a popular radio show in which callers would challenge him to answer their scientific questions. In the same spirit, he wrote 65 episodes of a television series that answered children’s science questions. He has also reported on science for newspapers and magazines, and is founding editor-in-chief of the magazine symmetry, which focuses on the world of particle physics, synchrotron x-ray science and cosmology. He is currently based in California at Stanford Linear Accelerator Center, which copublishes symmetry with Fermi National Accelerator Laboratory.